During World War II, the group was an Eighth Air Force heavy bombardment unit in England, stationed at RAF Eye. The group flew 158 combat missions, its last mission on 20 April 1945, after 5,000 sorties. It lost 22 aircraft.

The 490th BG combat in June 1944 with B-24's, bombing airfields and coastal defenses in France immediately preceding and during the invasion of Normandy. Then struck bridges, rail lines, vehicles, road junctions, and troop concentrations in France. Supported ground forces near Caen in July and near Brest in September 1944. Flew its last mission with the B-24 Liberator on 6 August 1944 when it struck V-1 launching sites in Basse Foret d'Eu, France

The group converted to B-17's in early August 1944 and flew its first mission with the B-17 on 27 August 1944 to Genshagen, Germany to attack the BMW Engine Factory - the 8th Air Force however was recalled due to weather.[1] It operated primarily against strategic targets until the end of February 1945. The 490th mounted attacks against enemy oil plants, tank factories, marshalling yards, aircraft plants, and airfields in such cities as Berlin, Hamburg, Merseburg, Münster, Kassel, Hannover, and Cologne. Interrupted strategic missions to attack supply lines and military installations during the Battle of the Bulge, December 1944 – January 1945. Beginning in March 1945, attacked interdictory targets and supported advancing ground forces.

After V-E Day, carried food to flood-stricken areas of the Netherlands and transported French, Spanish, and Belgian prisoners of war from Austria to Allied centers.

Redeployed US July 1945. Aircraft left RAF Eye on the 6 July 1945. The ground unit sailed from Southampton on the RMS Queen Elizabeth on the 26 August 1945 arriving New York 1 September 1945. The group was established at Drew Field, Florida on 3 September 1945 and inactivated there on 7 November.

The 490th BG did not have an official unit insignia approved by the United States Army Air Forces.[2]